The invention relates to improvements in methods of and in apparatus for making spacer frames for use between the panes of multiple-pane windows or the like. More particularly, the invention relates to improvements in methods and apparatus of the type disclosed in commonly owned U.S. Pat. Nos. 4,627,263 and 4,720,950 to Bayer et al.
It is known to convert elongated tubular blanks of ductile material into polygonal or otherwise configurated spacers or spacer frames which are at least partially filled with a flowable hygroscopic substance (desiccant) and are ready for insertion between the panes of a multiple-pane window. The desiccant prevents moisture which penetrates into a multiple-pane window from clouding the inner sides of the panes-which flank the spacer frame. It is further known to convert successive tubular blanks of ductile material into a series of substantially rectangular bodies prior to admission of flowable desiccant and to leave the ends of the thus deformed blanks open for admission of desiccant prior to conversion of such bodies into spacer frames. The arrangement is such that each rectangular body is formed with three bends, corners or elbows and the body is open in the region which is to constitute the fourth elbow of a rectangular spacer frame. This is desirable and advantageous because three elbows can be formed by simply bending the corresponding portions of the respective blanks. The fourth elbow is formed by moving the open ends of the rectangular body into abutment with each other. Presently known methods and apparatus employ connectors, which are used in the region of the fourth elbow to establish a seal and to thus prevent escape of admitted desiccant. The application of connectors is a complex and timeconsuming procedure which contributes significantly to the cost of spacer frames. Moreover, the elbows which are sealed by such connectors are frequent sources of leaks, i.e., desiccant is likely to escape from the multiple-pane window and/or into the space between the panes which flank the spacer frame.
Commonly owned published German patent application No. 32 21 986 of Bayer discloses an apparatus which is designed to make spacer frames and is provided with means for admitting a flowable desiccant into the internal spaces of tubular blanks prior to bending of such blanks into polygonal intermediate products or into finished spacer frames with one, two or more elbows. The spacer frames are sealed in regions between two neighboring elbows. This simplifies the sealing operation. However, bending of blanks which are filled with desiccant presents other problems; for example, a desiccantcontaining blank is likely to burst in the regions of the elbows. The aforementioned commonly owned U.S. Pat. Nos. 4,627,263 and 4,720,950 disclose means for reducing the likelihood of bursting of tubular blanks in regions where the blanks are bent to form elbows. Another possibility of reducing the likelihood of bursting of desiccant-containing tubular blanks in the regions of elbows is to increase the diameters of the elbows; this is not acceptable in many types of multiple-pane windows because the elbows are visible at the corners of the panes which flank such spacer frames. Moreover, apparatus of the type disclosed in U.S. Pat. Nos. 4,627,263 and 4,720,950 can be used with full advantage when the walls of hollow tubular blanks are sufficiently thick and when the material of the blanks exhibits a pronounced ductility. Such materials and thick-walled hollow tubular blanks contribute to the cost of spacer frames.
Published European patent application No. 0 252 066 of Lisec discloses a control system which can be used in apparatus for making multiple-pane windows with spacer frames between neighboring panes. The control system includes means for regulating the operation of the device which admits desiccant into the spacer frames. The extent to which a flowable desiccant is to fill the interior of a-spacer frame is not disclosed.
Published European patent application No. 0 197 468 of Lenhardt discloses a method of and an apparatus for making multiple-pane windows wherein the spacer frame is completely filled with a desiccant and is installed between two panes immediately after the making of perforations in the spacer frame is completed. The perforations enable the confined desiccant to absorb moisture which has penetrated into the space between the panes flanking the installed frame.
Swiss Pat. No. 642 713 to Brocking discloses a spacer frame which is practically completely filled with a granular desiccant. Such desiccant is admitted into the tubular blank prior to making of the elbows for conversion of the blank into a spacer frame.
European Pat. No. 0 103 111 to Glaser discloses a method of filling tubular blanks with a desiccant and of thereupon confining the introduced desiccant by injecting into selected portions of the blank blobs of a hardenable -adhesive prior to severing of the blank adjacent the thus obtained plugs.
Published German patent application No. 32 23 881 of Lisec discloses an apparatus for bending a tubular blank in such a way that the elbows exhibit portions having different radii of curvature.
Published German patent application No. 29 38 362 of Sernevi discloses an apparatus which admits granular material into hollow profiled bodies and is equipped with means for introducing sealing plugs into the open ends of profiled bodies so as to confine the supplies of granular material therein.
Published German patent application No. 26 44 852 of Schilling discloses apparatus for admitting metered quantities of desiccant into spacer frames for use between the panes of multiple-pane windows.
Published European patent application No. 0 195 176 of Lisec discloses specially designed valves which can be used to regulate the flow of desiccant into spacer frames for use in multiple-pane windows.
Published European patent application No. 0 009 703 of Wolflingseder discloses apparatus for providing a tubular blank with elbows in order to convert the blank into a spacer frame. The apparatus comprises a milling tool which cuts into the blank slits in the space between two clamping devices before the blank is bent in the region of the thus formed slots.